Combination of the names of Sarah Palin and her attorney Thomas Van Flein. rhymes with Van Halen.
has three meanings:
(a) someone who engages, (or communicates an intent to do so) in empty threats, legal (threatening to sue someone when there is no legal basis for doing so) or otherwise, in order to intimidate or cajole someone into complying with their wishes.
(b) the act of engaging in this sort of behavior.
(c)doing stupid, crazy-ass stuff in the public eye which only results in further embarrassing the party responsible. emphasis on the combination of being crazy AND stupid and crating a public spectacle.

person1: "did you catch the 4th of July weekend concert by Van Palin?"
person2: "yeah that chick is bat-shit crazy! i haven't seen a Van Palin like that since Tyson bit off part of Hollyfield's ear!"